It has been recognized by the battery art that the volumetric energy density of lead-acid batteries may be improved by increasing the number of electrodes present in a given cell volume. It has also been recognized that this may be accomplished through the provision of thinner electrodes. This principle has been used with "flat" or "pasted" type positive electrodes. However, it has not been successfully applied to tubular positive electrodes which are intended for heavy-duty, deep-discharge applications.
The life of a tubular positive electrode is primarily limited by the corrosion rate of the lead grid spines. Should a conventional tubular electrode be "scaled down" proportionately into a thinner configuration the corrosion rate will be increased due to the thinner active material portions surrounding the spines and, since the spines will also be proportionally thinner, total corrosion of the spines, resulting in failure of the electrode, will take place more quickly.